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  <title>Function to extract a sequence of default grapheme clusters from a text buffer, which must be encoded in UTF-8</title>
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  <div id="layout-content"><div id="function.grapheme-extract" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">grapheme_extract</h1>
  <p class="verinfo">(PHP 5 &gt;= 5.3.0, PHP 7, PECL intl &gt;= 1.0.0)</p><p class="refpurpose"><span class="refname">grapheme_extract</span> &mdash; <span class="dc-title">Function to extract a sequence of default grapheme clusters from a text buffer, which must be encoded in UTF-8</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.grapheme-extract-description">
  <h3 class="title">说明</h3>
  <p class="para">过程化风格</p>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>grapheme_extract</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$haystack</code></span>
   , <span class="methodparam"><span class="type">int</span> <code class="parameter">$size</code></span>
   [, <span class="methodparam"><span class="type">int</span> <code class="parameter">$extract_type</code></span>
   [, <span class="methodparam"><span class="type">int</span> <code class="parameter">$start</code><span class="initializer"> = 0</span></span>
   [, <span class="methodparam"><span class="type">int</span> <code class="parameter reference">&$next</code></span>
  ]]] ) : <span class="type">string</span></div>

  <p class="para rdfs-comment">
   Function to extract a sequence of default grapheme clusters from a text buffer, which must be encoded in UTF-8. 
  </p> 
  </div>


 <div class="refsect1 parameters" id="refsect1-function.grapheme-extract-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<code class="parameter">haystack</code></dt>

     <dd>

      <p class="para">
       String to search.
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">size</code></dt>

     <dd>

      <p class="para">
       Maximum number items - based on the $extract_type - to return.
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">extract_type</code></dt>

     <dd>

      <p class="para">
       Defines the type of units referred to by the $size parameter:
      </p>
       <p class="para">
        <ul class="simplelist">
         <li class="member">GRAPHEME_EXTR_COUNT (default) - $size is the number of default
         grapheme clusters to extract.</li>
         <li class="member">GRAPHEME_EXTR_MAXBYTES - $size is the maximum number of bytes
         returned.</li>
         <li class="member">GRAPHEME_EXTR_MAXCHARS - $size is the maximum number of UTF-8
         characters returned.</li>
        </ul>
       </p>
     </dd>

    
    
     <dt>
<code class="parameter">start</code></dt>

     <dd>

      <p class="para">
       Starting position in $haystack in bytes - if given, it must be zero or a
       positive value that is less than or equal to the length of $haystack in
       bytes, or a negative value that counts from the end of $haystack.
       If $start does not point to the first byte of a UTF-8
       character, the start position is moved to the next character boundary.
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">next</code></dt>

     <dd>

      <p class="para">
       Reference to a value that will be set to the next starting position.
       When the call returns, this may point to the first byte position past the end of the string.
      </p>
     </dd>

    
 
   </dl>

  </p>
 </div>

   
 
 <div class="refsect1 returnvalues" id="refsect1-function.grapheme-extract-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   A string starting at offset $start and ending on a default grapheme cluster
   boundary that conforms to the $size and $extract_type specified.
  </p>
 </div>

 
 <div class="refsect1 changelog" id="refsect1-function.grapheme-extract-changelog">
  <h3 class="title">更新日志</h3>
  <table class="doctable informaltable">
   
    <thead>
     <tr>
      <th>版本</th>
      <th>说明</th>
     </tr>

    </thead>

    <tbody class="tbody">
     <tr>
      <td>7.1.0</td>
      <td>
       Support for negative <code class="parameter">start</code>s has been added.
      </td>
     </tr>

    </tbody>
   
  </table>

 </div>


 <div class="refsect1 examples" id="refsect1-function.grapheme-extract-examples">
  <h3 class="title">范例</h3>
  <div class="example" id="example-3093">
   <p><strong>Example #1 <span class="function"><strong>grapheme_extract()</strong></span> example</strong></p>
   <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br />$char_a_ring_nfd&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">"a\xCC\x8A"</span><span style="color: #007700">;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;'LATIN&nbsp;SMALL&nbsp;LETTER&nbsp;A&nbsp;WITH&nbsp;RING&nbsp;ABOVE'&nbsp;(U+00E5)&nbsp;normalization&nbsp;form&nbsp;"D"<br /></span><span style="color: #0000BB">$char_o_diaeresis_nfd&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">"o\xCC\x88"</span><span style="color: #007700">;&nbsp;</span><span style="color: #FF8000">//&nbsp;'LATIN&nbsp;SMALL&nbsp;LETTER&nbsp;O&nbsp;WITH&nbsp;DIAERESIS'&nbsp;(U+00F6)&nbsp;normalization&nbsp;form&nbsp;"D"<br /><br /></span><span style="color: #007700">print&nbsp;</span><span style="color: #0000BB">urlencode</span><span style="color: #007700">(</span><span style="color: #0000BB">grapheme_extract</span><span style="color: #007700">(&nbsp;</span><span style="color: #0000BB">$char_a_ring_nfd&nbsp;</span><span style="color: #007700">.&nbsp;</span><span style="color: #0000BB">$char_o_diaeresis_nfd</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">GRAPHEME_EXTR_COUNT</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
   </div>

  </div>
  <p class="para">以上例程会输出：</p>
  <div class="example-contents screen">
<div class="cdata"><pre>
o%CC%88
</pre></div>
  </div>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.grapheme-extract-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="grapheme_substr.html" class="function" rel="rdfs-seeAlso">grapheme_substr()</a> - Return part of a string</span></li>
     <li class="member">
      <a href="http://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries" class="link external">&raquo;&nbsp;
       Unicode Text Segmentation: Grapheme Cluster Boundaries
      </a>
     </li>
   </ul>
  </p>
 </div>

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